JP2004019103A - Buoyancy adjustment structure of hollow structure for underwater installation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a buoyancy adjustment structure of a hollow construction for underwater installation which facilitates manufacture of constructions and maintenance of machines and facilities, and reduces labor. <P>SOLUTION: In this buoyancy adjustment structure of the hollow construction 20 for underwater installation which adjusts buoyancy in water of the construction 20 formed like a hollow case by pouring water into and draining water from a hollow part 21, a pouring and draining port 23 communicated with the hollow part 21, while the part can be opened and closed by an opening and closing valve 24, is provided in a lower part of a peripheral wall 20a of the structure 20, and a pressure adjusting means 25 for increasing or decreasing pressure in the hollow part 21 is provided outside the structure 20. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a buoyancy adjusting structure for a hollow structure for underwater installation, such as a caisson that is pulled from the production place to an installation place and moves underwater, and a temporary structure temporarily installed on the bottom of the water for revetment or the like.
[0002]
[Prior art]
Conventionally, the place of manufacture and the place of installation are different. For underwater installations such as caisson that is pulled from the place of manufacture to the place to be moved and temporary structures that are temporarily installed for the purpose of revetment and then removed. The hollow structure is provided with a structure capable of adjusting its own buoyancy, and the buoyancy adjustment structure enables suitable movement in water and installation work.
[0003]
As a buoyancy adjusting structure, for example, a water injection / drainage device 2 is provided in a hollow box-shaped underwater installation hollow structure 1 (caisson) shown in FIG. 4 and the device 2 is used to pour water into and out of a hollow portion 1a of the structure. There is one that performs buoyancy adjustment by using the following method. The water injection / drainage device 2 includes a pump 5 operated by a motor 4 connected via a speed reducer 3, and operates the pump 5 with the water injection on-off valves 6a and 6b open to provide a structure. (1) External water is sucked by the pump 5 and taken in from the outer water inlet 7a, and is injected into the hollow portion 1a through the hollow side water inlet 7b, while the drainage on-off valve 8a, By operating the pump 5 with the opening 8b open, the water in the hollow portion 1a is sucked by the pump 5 and taken in from the hollow side drain port 9a, and passes through the outer drain port 9b to the outside of the structure 1. It is designed to be drained. In addition, reference numeral 10 in the figure is a pipe connecting each pouring and discharging port and the pump.
[0004]
[Problems to be solved by the invention]
However, in the conventional technology as described above, the internal structure for installing the mechanical equipment constituting the pouring and draining device 2 such as the speed reducer 3, the motor 4, the pump 5, and the pipe 10 in the hollow portion 1a of the structure is required. In order to install the speed reducer 3 and the motor 4 that are complicated and dislike moisture, it is necessary to provide the watertight chamber 11 for protecting them in the caisson 1. Therefore, the manufacturing cost of the structure 1 is high, and Work inside the structure, such as when the structure is manufactured or when the equipment is maintained, is a closed work, so that there is a problem that the efficiency is low.
[0005]
Further, this type of pouring / draining device has a problem that energy (electric power) used for its operation is large and efficiency is low.
[0006]
The present invention has been made in view of the situation of the related art, and has an object to provide a buoyancy adjusting structure of a hollow structure for underwater installation, which can make the production of a structure and maintenance of mechanical equipment cheap and easy and save labor. And
[0007]
[Means for Solving the Problems]
In order to solve the conventional problems as described above and to achieve the intended object, the invention of claim 1 is to provide a structure in which a hollow box is formed by pouring and discharging water into the hollow portion of the structure. In the buoyancy adjustment structure of a hollow structure for underwater installation configured to perform buoyancy adjustment in the lower part of the peripheral wall of the structure, with an injection port that communicates with the hollow portion in a state that can be opened and closed by an on-off valve, A pressure adjusting means for increasing and decreasing the pressure in the hollow portion is provided outside the structure.
[0008]
With this configuration, the configuration inside the structure can be simplified, and the manufacturing cost of the structure is reduced. In addition, a free space is created in the hollow portion of the structure, and the manufacture of the structure, maintenance of mechanical equipment in the structure, and the like can be easily performed. Further, the pressure difference caused by the head difference between the water level in the hollow part and the external water level can be used for pouring and draining into the hollow part, so that labor is saved. Further, since the pressure adjusting means is installed outside the structure, maintenance of the pressure adjusting means can be suitably performed.
[0009]
According to a second aspect of the present invention, in the first aspect of the invention, the pressure adjusting means uses an air compressor or a blower, so that the pressure in the hollow portion can be suitably increased or decreased.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of a buoyancy adjusting structure for a hollow structure for underwater installation according to the present invention will be described with reference to the drawings.
[0011]
FIG. 1 schematically shows a hollow structure for underwater installation having a buoyancy adjusting structure according to the present invention, and reference numeral 20 denotes a caisson.
[0012]
The caisson 20 is formed in a hollow box shape from concrete, and buoyancy is adjusted by pouring and draining the hollow portion 21. It is desirable that the hollow portion 21 of the caisson 20 has high airtightness, and the hollow portion 21 may be partitioned by partition walls 22, 22.
[0013]
At the lower part of the peripheral wall 20 a of the caisson 20, filling and discharging ports 23, 23 are provided in communication with the hollow portion 21.
[0014]
The pouring and discharging port 23 is opened and closed by an on-off valve 24, and when the on-off valve 24 is in an open state, the hollow portion 21 of the caisson 20 is in a state of communicating with the outside through the pouring and discharging port 23. When the 24 is in the closed state, the hollow portion 21 of the caisson 20 is blocked from the outside of the caisson.
[0015]
Further, outside the caisson 20, a pressure adjusting means 25 for increasing and decreasing the pressure in the hollow portion 21 is provided.
[0016]
The pressure adjusting means 25 is provided on the upper surface of the caisson 20 and uses an air supply / exhaust device 26 using an air compressor or a blower, and presses or discharges air into or from the hollow portion 21 through the connecting pipe 27. Thus, the pressure in the hollow portion 21 is increased or decreased. That is, the air in the hollow portion 21 is sucked by the air supply / exhaust device 26 and exhausted to the outside, so that the air is exhausted from the hollow portion, whereby the pressure in the hollow portion 21 is reduced. External air is taken in by the device 26 and the compressed air is supplied into the hollow portion 21 so that the inside of the hollow portion 21 is pressurized.
[0017]
Note that a turbo blower, a turbo pump, or the like can be used as the air compressor or the blower.
[0018]
Next, a method for injecting water into the hollow portion 21 of the caisson 20 will be described with reference to FIG.
[0019]
First, the opening / closing valve 24 is opened, and the hollow portion 21 is brought into a state of communicating with the outside of the caisson 20 through the pouring / draining port 23. As shown in FIG. 2A, since the water level in the hollow portion 21 is lower than the water level outside the caisson, the pressure in the hollow portion 21 is reduced by the pressure difference caused by the head difference h, and the pressure causes the hollow portion 21 to be depressurized. Water injection into the inside is started.
[0020]
Next, the inside of the hollow portion 21 is depressurized by the pressure adjusting means 25 and water is injected. That is, the air in the hollow portion 21 is sucked by operating the air supply / exhaust device 26, and the air in the hollow portion 21 is exhausted to reduce the pressure in the hollow portion 21.
[0021]
In this manner, as shown in FIG. 2B, until the water head difference h becomes zero, that is, until the water level outside the caisson 20 and the water level inside the hollow portion 21 become the same, Water injection by reduced pressure and water injection by natural water pressure generated by the head difference h are performed. Therefore, the efficiency of water injection is higher than that performed only by the pressure adjusting means, and energy (electric power) required for water injection can be saved.
[0022]
After the head difference h becomes zero, water injection is performed only by reducing the pressure in the hollow portion 21 by the pressure adjusting means 25 (FIG. 2C).
[0023]
Then, when the water level reaches the desired height, the on-off valve 24 is closed to shut off the hollow portion 21 from the outside, the pressure adjusting means 25 is stopped, and the water injection work is completed.
[0024]
Next, a method of draining water from the hollow portion 21 of the caisson 20 will be described with reference to FIG.
[0025]
First, as shown in FIG. 3A, the on-off valve 24 is opened, and the hollow portion 21 is brought into communication with the outside of the caisson 20 through the pouring / draining port 23. In this state, if the water level in the hollow portion 21 is higher than the water level outside the caisson, the inside of the hollow portion 21 is pressurized by the pressure difference generated by the head difference H, and the pressure starts draining from the hollow portion 21. Is done.
[0026]
Next, the inside of the hollow portion 21 is pressurized by the pressure adjusting means 25 to drain water. That is, the air supply / exhaust device 26 is operated to take in outside air into the device 26, compress the taken-in air and supply the compressed air into the hollow portion 21, thereby pressurizing the inside of the hollow portion 21 to perform drainage.
[0027]
In this manner, until the head difference H becomes zero, that is, until the water level outside the caisson 20 and the water level in the hollow portion 21 become the same, the drainage by pressurization in the hollow portion 21 of the pressure adjusting means 25 is performed. And drainage by natural water pressure caused by the head difference H is performed.
[0028]
After the head difference H becomes zero, drainage is performed only by pressurizing the hollow portion 21 by the pressure adjusting means 25 (FIG. 3B).
[0029]
After draining by a desired amount, the on-off valve 24 is closed to shut off the hollow portion 21 from the outside and stop the pressure adjusting means 25, thereby completing the draining operation (FIG. 3 (c)).
[0030]
The caisson 20 is capable of adjusting buoyancy in water by injecting and draining water into the hollow portion 21 of the caisson 20 as described above.
[0031]
In the above-described embodiment, the concrete caisson has been described. However, the material of the structure may be another material such as steel as long as it is a hollow box.
[0032]
Further, in the above-described embodiment, the example in which the air supply / exhaust device 26 is installed on the upper surface of the caisson 20 is described. However, the air supply / exhaust device may be installed on a barge or on the ground separately from the caisson 20.
[0033]
In the above-described embodiment, in the pouring and draining process, the example in which the natural pressure caused by the head difference and the pressure by the pressure adjusting means are simultaneously applied until the head difference disappears, but only the natural pressure is applied until the head difference disappears. , And after the head difference has disappeared, the pressure adjusting means may be used.
[0034]
【The invention's effect】
As described above, the buoyancy adjusting structure of the hollow structure for underwater installation according to the present invention includes the pressure adjusting means outside, so that it is not necessary to provide a watertight chamber inside the structure, and the space required for maintenance work and the like is eliminated. Can be sufficiently secured, work efficiency is improved, and costs for maintenance and the like are reduced. In addition, the manufacturing cost is reduced because the structure is simplified. Further, since the pressure adjusting means is provided outside, maintenance of the pressure adjusting means can be suitably performed.
[0035]
Since the pressure difference generated by the water head difference is used for the filling and draining in the hollow portion, not only the pressure adjusting means, but labor is saved as compared with the case where the filling and draining is performed only by the pressure adjusting means.
[Brief description of the drawings]
FIG. 1 is a sectional view schematically showing a caisson having a buoyancy adjusting structure for a hollow structure for underwater installation according to the present invention.
FIG. 2 is a schematic cross-sectional view for explaining an operation of pouring water into a structure using the buoyancy adjusting structure according to the present invention.
FIG. 3 is a schematic cross-sectional view for illustrating a drainage operation from inside the structure.
FIG. 4 is a sectional view schematically showing a caisson having a conventional buoyancy adjusting structure.
[Explanation of symbols]
20 caisson (hollow structure for underwater installation)
20a Peripheral wall 21 Hollow portion 22 Partition wall 23 Injection / drainage port 24 On-off valve 25 Pressure adjusting means 26 Supply / exhaust device 27 Connecting pipe

Claims (2)

In the buoyancy adjustment structure of a hollow structure for underwater installation, which performs buoyancy adjustment in water of the structure by pouring and draining into the hollow portion of the structure formed in a hollow box shape,
A lower portion of the peripheral wall of the structure is provided with a pouring / draining port communicating with the hollow portion so as to be openable and closable by an on-off valve, and a pressure adjusting means for increasing and decreasing the pressure in the hollow portion is provided outside the structure. A buoyancy adjustment structure for hollow structures for underwater installations, characterized by: The buoyancy adjustment structure of a hollow structure for underwater installation according to claim 1, wherein the pressure adjustment means uses an air compressor or a blower.

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